I removed the "@" which started the mkdir instruction line 219 in FeedForAll_Scripts_CachingExtension.php release v 3.14 2009/02/22 20:50:39.
So I think I have an authorization error to create a temp cache directory, even if I do not want to use caching (flag $useOutputCaching = 0;)
Looks like a bug.

The php script produced by RssMesh is NOT a stand-alone rss2html-like php script, which would build and display the resulting data on the user screen, it builds an actual RSS feed, sum of all input feeds.

So, to display the contents of the feeds, the php script should be used as an INPUT feed, nothing else.